i have a 1995 gmc 3500 pickup ,transmission in limp mode,no speedometer,abs light comes on,have no power to #20 and #14 fuses. have replaced speed sensor,ignition switch still no power to fuses. checked yellow ignition wire coming out of bottom of ignition switch no. Guntis – Yes, you can use a PIC18F4550. The architecture is the same, as is the memory mapping. All that you need to do is double check the pin definitions and change the device include at the top of the source code to: #include <18F4550.h> before you recompile..